What is Macula?
The macula makes up only a small part of the retina, yet it is much more sensitive to detail than the rest of the retina (called the peripheral retina). The macula is what allows you to thread a needle, read small print, and read street signs. The peripheral retina gives you side (or peripheral) vision. If someone is standing off to one side of your vision, your peripheral retina helps you know that person is there by allowing you to see their general shape.
Many older people develop macular degeneration as part of the body's natural aging process. There are different kinds of macular problems, but the most common is age-related macular degeneration.
What are the Symptoms of AMD?
With macular degeneration, you may have symptoms such as blurriness, dark areas or distortion in your central vision, and perhaps permanent loss of your central vision. It usually does not affect your side, or peripheral vision. For example, with advanced macular degeneration, you could see the outline of a clock, yet may not be able to see the hands of the clock to tell what time it is.
What are the Causes of AMD?
Causes of macular degeneration include the formation of deposits called drusen under the retina, and in some cases, the growth of abnormal blood vessels under the retina. With or without treatment, macular degeneration alone almost never causes total blindness. People with more advanced cases of macular degeneration continue to have useful vision using their side, or peripheral vision. In many cases, macular degeneration's impact on your vision can be minimal.
When macular degeneration does lead to loss of vision, it usually begins in just one eye, though it may affect the other eye later.
What are the Types of AMD?
Dry form: The "dry" form of macular degeneration is characterized by the presence of yellow deposits, called drusen, in the macula. A few small drusen may not cause changes in vision; however, as they grow in size and increase in number, they may lead to a dimming or distortion of vision that people find most noticeable when they read. In more advanced stages of dry macular degeneration, there is also a thinning of the light-sensitive layer of cells in the macula leading to atrophy, or tissue death. In the atrophic form of dry macular degeneration, patients may have blind spots in the center of their vision. In the advanced stages, patients lose central vision.
Wet form:The "wet" form of macular degeneration is characterized by the growth of abnormal blood vessels from the choroid underneath the macula. This is called choroidal neovascularization. These blood vessels leak blood and fluid into the retina, causing distortion of vision that makes straight lines look wavy, as well as blind spots and loss of central vision. These abnormal blood vessels and their bleeding eventually form a scar, leading to permanent loss of central vision.
How is Macular Degeneration is diagnosed?
Age-related macular degeneration can be detected in a routine eye exam. One of the most common early signs of macular degeneration is the presence of drusen -- tiny yellow deposits under the retina -- or pigment clumping. Your doctor can see these when examining the eyes. Your doctor may also ask you to look at an Amsler grid -- a pattern of straight lines that resemble a checkerboard. Some of the straight lines may appear wavy to you, or you may notice that some of the lines are missing. These can be signs of macular degeneration.
If your doctor detects age-related macular degeneration, you may have a procedure called angiography or an OCT. In angiography, a dye is injected into a vein in the arm. Photographs are taken as the dye reaches the eye and flows through the blood vessels of the retina. If there are new vessels or vessels leaking fluid or blood in the macula, the photographs will show their exact location and type. OCT is able to see fluid or blood underneath the retina without using dye.
How is Macular Degeneration is treated?
With “dry” macular degeneration, the tissue of the macula gradually becomes thin and stops functioning properly. There is no cure for dry AMD, and any loss in central vision cannot be restored. However, doctors now believe there is a link between nutrition and the progression of dry AMD. Dietary changes favoring low-fat content and dark green leafy vegetables can slow vision loss. Nutritional supplements also may be beneficial.
Less common, “wet” macular degeneration results when fluids leak from newly formed blood vessels under the macula and blur central vision. Vision loss can be rapid and severe. If detected early, “wet” AMD can be treated with laser treatment, which is often called photocoagulation. A highly focused beam of light seals the leaking blood vessels that damage the macula. Photodynamic Therapy (PDT) uses a medication injected into the bloodstream, which is then activated with a laser shone into the eye. A new therapy available, where a medication is injected into the back of the eye, is showing favorable results. These are not permanent cures but are used to slow the rate of central vision loss.
Age-Related Macular Degeneration (AMD) is the leading cause of severe vision loss in adults over age 50. The Centers for Disease Control and Prevention estimate that 1.8 million people have AMD and another 7.3 million are at substantial risk for vision loss from AMD. Caucasians are at higher risk for developing AMD than other races. Women also develop AMD at an earlier age than men. This eye disease occurs when there are changes to the macula, a small portion of the retina that is located on the inside back layer of the eye. AMD is a loss of central vision that can occur in two forms: “dry” or atrophic and “wet” or exudative.
Most people with macular degeneration have the dry form, for which there is no known treatment. The less common wet form may respond to laser procedures, if diagnosed and treated early.
Some common symptoms are: a gradual loss of ability to see objects clearly, distorted vision, a gradual loss of color vision, and a dark or empty area appearing in the center of vision. If you experience any of these, contact your doctor of optometry immediately for a comprehensive examination. Central vision that is lost to macular degeneration cannot be restored. However, low vision devices, such as telescopic and microscopic lenses, can be prescribed to maximize existing vision.
Researchers have linked eye-friendly nutrients such as lutein/zeaxanthin, vitamin C, vitamin E, and zinc to reducing the risk of certain eye diseases, including macular degeneration.